Yes. The Quran commands returning trusts to their owners (4:58) and forbids betraying them (8:27). This includes money left with you, secrets, and the duties of a job. Delaying payment of a debt when you are able to pay is also a form of injustice.
Sesungguhnya Allah menyuruh kamu supaya menyerahkan segala jenis amanah kepada ahlinya (yang berhak menerimanya), dan apabila kamu menjalankan hukum di antara manusia, (Allah menyuruh) kamu menghukum dengan adil. Sesungguhnya Allah dengan (suruhanNya) itu memberi pengajaran yang sebaik-baiknya kepada kamu. Sesungguhnya Allah sentiasa Mendengar, lagi sentiasa Melihat.
Wahai orang-orang yang beriman! Janganlah kamu mengkhianati (amanah) Allah dan RasulNya, dan (janganlah) kamu mengkhianati amanah-amanah kamu, sedang kamu mengetahui (salahnya).
This is general information, not a fatwa. For your own situation, ask a qualified scholar.
Questions about halal and haram
Is it haram to betray a trust?
Yes. The Quran commands returning trusts to their owners (4:58) and forbids betraying them (8:27). This includes money left with you, secrets, and the duties of a job. Delaying payment of a debt when you are able to pay is also a form of injustice.
